FOOT FOR A ROTATABLE CHAIR

Abstract: The present invention is related to a foot for a rotatable chair incorporating a hub (1) for the chair center rod (2), and a base part with an essentially trumpet-shaped contour suited for upholstering with leather or similar material. The chair foot is characterized in that the foot comprises a trumpet-shaped center part (3) made from injection-moulded material, an outer rim part (4) suited to accommodate the insertion of said center part (3) in such a manner that the contours of both parts (3, 4) adjoin forming the entire trumpet-shaped contour of the chair foot, and further comprises a circular bottom plate (5) to which said parts (3, 4) of the foot are fixed.

Description: Foot for a rotatable chair The present invention relates to a foot for a rotatable chair incorporating a hub for the center rod of the chair seat cushion part, and particularly, a base part with an essentially trumpet-shaped contour suited for upholstering with leather or similar material. The invention is parti¬ cularly related to a base for a TV chair or similar upholstered furniture. In prior-art foot constructions of cited type of chairs, the base either has a full-metal structure, or alternative¬ ly, comprises a metal stem with a vertical hub suited to accommodate the center shaft of the chair and two square, horizontal, metal support plates which are centered at the stem and are vertically displaced from each other by a given distance, whereby the stem extends through the centerpoint of said plates. Between said support plates are adapted a number of circular pieces of wood so placed and shaped that they provide the peripheral contour of the trumpet-shaped base of the chair. Above the upper support plate is adapted a bearing piece of slightly resilient material and so contoured as to form the inner part of the trumpet-shaped base. Manufacture of such a chair base is extremely complicated and labour-intensive resulting in relatively high production costs. It is an object of present invention to overcome the above- described problems and to provide a stable and durable chair foot with a desired trumpet-shape whose production is quick and simple at a reasonable price. This goal is achieved by a chair foot characterized in that said chair foot comprises a trumpet-shaped center part made from injection-moulded material, an outer rim part suited to accommodate the insertion of said center part in such a manner that the contours of both parts adjoin forming the entire trumpet-shaped contour of the chair foot, and further comprises a circular bottom plate to which said parts of the foot are fixed. Other characterizing properties of the invention are disclosed in the annexed claims 1 - 9. The invention is next examined in greater detail with reference to the appended drawings, in which: Figure 1 is a sectional side view of an exemplifying embodiment of the chair foot according to the invention; Figure 2 is a top view of the chair foot shown in Fig. 1; Figure 3 is a bottom view of the chair foot shown in Fig. 1; Figure 4 is a sectional view of a second embodiment of the chair foot according to the invention; and Figure 5 is a sectional view of a third embodiment of the chair foot according to the invention. The chair foot according to the invention includes a hub 1 for the center rod 2 of a rotatable chair, said chair foot having an essentially trumpet-shaped contour suited for upholstering with leather or similar upholstering material. The characterizing property of the chair foot according to the invention is that said chair foot comprises a trumpet- shaped center part 3 fabricated from injection-moulded material, an outer rim part 4 adapted to accommodate the insertion of said center part 3 in such a manner that the contours of both parts 3, 4 adjoin forming the entire trumpet-shaped contour of the chair foot, and further comprises a circular bottom plate 5 to which said parts 3 and 4 of the foot are fixed. By manufacturing the center part 3 from an injection- moulded material, advantageously a composite material such as a glass-fiber-reinforced thermoplastic of extremely high strength, the center part 3 can be advantageously provided with a center cavity suited act as a pivot hub 1 for the center rod 2 of the chair seat cushion part. Suitable thermoplastic for the center part is polypropylene, poly- amide or polycarbonate. Sufficient stability is attained by using a number of vertical and radial stiffening ribs 6 which join the outer wall of the chair hub 1 to the inner side of the contoured envelope of the center part 3. In certain cases the center part 3 can be alternatively made from injection-moulded aluminium or zinc. The rim part 4 which will not be subjected to as high mechanical stresses as the center part 3 can be advantageously injection- moulded from a less costly material such as conventional polypropylene or similar thermoplastic polymer. The base plate 5 can be advantageously made from plywood or similar wood material which makes it possible to fix the lower edge of the upholstering material to the underside of the base plate 5. When desired, the base plate 5 and the rim part 4 may be fabricated as a single piece from, e.g., wood, whereby only the contour of the center part 3 will be upholstered with leather or similar material. To attain the best possible mating between the center part 3 and the rim part 4, the upper part of the inner mating surface 7 may be provided with a rabbet 8 running along the entire inner rim of the rim part 4, said rabbet having a diameter compatible with the outer diameter of the center part 3 and its horizontal dimension being compatible with the height of the outer rim of the center part 3. By virtue of such a construction, the same center part 3 can be used in conjunction with rim parts 4 of different height and contour of their contour envelope (cf. Fig. 1 and Fig 4). To attain the best possible stability, the chair foot can be advantageously provided with a spacing element 15 placed in the space remaining between the stiffening ribs 6 of the center part and the base plate 5. A suitable method of connecting the different elements of the chair foot to each other is by means of screws, e.g., by designing each stiffening rib 6 closest to the perimeter of the center part 3 with a thicker area in which a screw hole 9 is provided. By virtue of the rabbet 8 of the rim part 4, the rim part 4 will be fixed to the base plate 5 when the base plate 5 is fixed by screws to the center part 3. A suitable number of the stiffening ribs 6, and con¬ sequently, the screw holes 9 is five or six as illustrated in Fig. 3. In the simplest embodiment, the central cavity of the center part 3 is formed into a chair hub 1 suited to accommodate the conventional chair seat cushion part center rod 2, whereby the cavity has a diameter compatible with the diameter of the center rod 2. In a more advanced embodiment, the center rod 2 may be of the type equipped with a return mechanism such as that illustrated in the drawing, whereby a slightly larger cylindrical cavity must be provided in the center part 3 so that an spring-loaded, axially movable sliding element 10 placed about the center rod 2 can be adapted to the interior of the chair hub 1, said sliding element 10 having at its lower end a spiral cam surface 11 adapted to cooper¬ ate with a follower roll 12 mounted on the center rod 2, thus forming a return mechanism of the type described in, e.g., the FI patent publication 83,590. To achieve a reliable and durable construction, the lower part of the chair hub 1 is provided with a bearing seat compatible with the lower end of the center rod 4, said bearing seat acting as a sliding bearing for the center rod 4, while the upper part of the chair hub 1 is provided with a ball bearing 13. According to a preferred embodiment, the top of the center part 3 is provided with a collar 14 adapted about the chair hub 1, said collar having a contour which acts as a continuation of the trumpet-shaped contour of the chair base proper. This collar principally serves for three functions, one of which is to mask the point where the chair seat cushion part adjoins the chair base, while the collar on the other hand also facilitates an effective and simple fixing of a shape-sewn leather upholstery tensioned over the chair base. This fixing takes place by folding the upper rim of the leather upholstery over the collar 14 into a cavity formed into the collar 14, after which an annular compression spring is inserted to tension the rim of the leather upholstery against the inner wall of the collar 14.

Claims: Claims : 1. A foot for a rotatable chair incorporating a hub (1) for the chair center rod (2), and particularly, a base part with an essentially trumpet-shaped contour suited for upholstering with leather or similar material, c h a r ¬ a c t e r i z e d in that the foot comprises a trumpet- shaped center part (3) made from injection-moulded material, an outer rim part (4) suited to accommodate the insertion of said center part (3) in such a manner that the contours of both parts (3, 4) adjoin forming the entire trumpet-shaped contour of the chair foot, and further comprises a circular bottom plate (5) to which said parts (3, 4) of the foot are fixed. 2. A chair foot as defined in claim 1, c h a r a c ¬ t e r i z e d in that the inner mating surface (7) of the rim part (4) is provided with a rabbet (8) running along the entire inner rim of the rim part (4), said rabbet having a diameter compatible with the outer diameter of the center part (3) and its horizontal dimension being compatible with the height of the outer rim of the center part (3). 3. A chair foot as defined in claim 2, c h a r a c ¬ t e r i z e d in that the three major elements (3, 4, 5) of the chair foot are fixed together by means of screws (9) connecting the base plate (5) to the center part (3). 4. A chair foot as defined in claim 3, c h a r a c ¬ t e r i z e d in that the center part (3) is designed to act as a hub (1) for a conventional center rod (2) of the chair seat cushion part. 5. A chair foot as defined in claim 3, c h a r a c ¬ t e r i z e d in that the center part (3) is designed to act as a hub (1) for a return-spring-loaded center rod (2) of the chair seat cushion part. 6. A chair foot as defined in any foregoing claim, c h a r a c t e r i z e d in that the top of the center part (3) is provided with a collar (14) adapted about the chair hub (1), said collar having a contour which acts as a continuation of the trumpet-shaped contour of the chair foot proper. 7. A chair foot as defined in any foregoing claim, c h a r a c t e r i z e d in that the center part (3) is manufactured from a composite material comprising a glass- fiber-reinforced thermoplastic such as polypropylene, polyamide or polycarbonate. 8. A chair foot as defined in any of foregoing claims 1 - 6, c h a r a c t e r i z e d in that the center part (3) is manufactured from aluminium or zinc. 9. A chair foot as defined in claim 6, c h a r a c ¬ t e r i z e d in that a shape-sewn leather upholstery tensioned over the chair foot is fixed at the top of the chair foot by means of an annular compression spring which is placed into a cavity designed to the interior of said collar (14) so as to compress the upper rim of the leather upholstery folded over the collar (14) and the upholstery is fixed at its lower rim by stapling to the underside of the base plate (5).

Inventors: KJELLMAN HELENA, KJELLMAN, HELENA
Applicants: KJELLMAN HELENA, KJELLMAN, HELENA
Application year: 1994
Main classification: A47C3
IPC codes: A47C3, A47C7